Patients with cerebrovascular insufficiency (transient ischemic attacks) related to atherosclerosis, fluctuations in blood pressure, and intermittent cardiac dysrhythmias, are being studied to determine the degree to which these possible precipitants actually trigger episodes of cerebrovascular insufficiency. Patients are studied by a variety of clinical investigations, including radiographic procedures, radioisotopic and pharmacological studies, as well as prolonged monitoring of electrocardiogram and systolic blood pressure. Neuropsychological and behavioral studies of patients with TIA's and cerebral infarctions are being studied to ascertain the degree to which cerebrovascular disease affects performance.